Shoulder harness for artificial arms



April 15, 1952 s. w. ALDERSO N 2,592,842

SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 15 Sheets-Sheet l O [0 Q U.

W) w 0 i L) INVENTOR Jam 5482' Mfliderson.

WAW

April 15, 1952 s. w. ALDERSON SHOULDER HARNESS FOR ARTIFICIAL ARMS 15 Sheets-Sheet 2 Original Filed July 10, 1948 INVENTOR SamueZ l k'flidersoiz.

AGENT April 15, 1952 s. w. ALDERSON 2,592,842

SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 15 Sheets-Sheet 5 ELBOW PIVOT ELBOW new:

S ELECTOH SWITCH I7IX r7i CLUTCH SELECTOR Fuss.

CLUTCHES HAND FLEX DRIVE PRONATI DRIVE FINGER PIVOT INDEX FINGER INVENTOR 'ai'nkel Wflldarson QPQI A. M

AGENT S. W. ALDERSON SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 April 15, 1952 I5 Sheets-Sheet 4 mN u En 26nd www m3 25231 m ma .25 5:2 5520mm Nam INVENTQR Samuel l lffliderb'vr'a' BY W W April 15, 1952 s. w. ALD ERSON SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 15 Sheets-Sheet 5 April 15, 1952 s. w. ALDERSQN SHOULDER HARNESS FOR ARTIFICIAL ARMS l5 Sheets-Sheet 6 Original'Filed July 10, 1948 INVENTOR Jamuei Wflldenson BY w fiw April 5, 1952 s. w. ALDER'SON 2,592,842

SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 15 Sheets-Sheet 7 S. W. ALDERSON SHOULDER HARNESS FOR ARTIFICIAL ARMS April 15, 1952 15 Sheets-Sheet 8 Original Filed July 10, 1948 Nmx INVENTOR JamzzaZlI/filderswz April 15, 1952 s. w. ALDERSON 4 2,592,842

SHOULDER HARNESS FOR ARTIFICIAL ARMS 15 Sheets$heet 9 Original Filed July 10, 1948 INVENTOR Jamzzel Wflldersoll.

4 BY WAW April 15, 1952 S. W. ALDER-SON SHOULDER HARNESS FOR ARTIFICIAL ARMS l5 Sheets-Sheet 10 Original Filed July 10, 1948 INVENTOR Jam ue-Z W/Yldcrson.

April 15, 1952 s. WIALDERSON SHOULDER HARNESS FOR ARTIFICIAL ARMS l5 Sheets-Sheet 11 Original Filed July 10, 1948 FIG.29

April 15, 1952 s. w. ALDERSON 2,592,842

SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 15 Sheets-Sheet 12 INVENTOR Samuel Wflidersbr'z A ril 15, 1952 s. w. ALDERSON SHOULDER HARNESS FOR ARTIFICIAL ARMS l5 Sheets-Sheet 13 Original Filed July 10, 1948 n o 2 m A R e w mwm mm T N w m Q w W A P231 2: 20 d 52E 33 M Y W a m B J @w illlllliilTl ll J 3m JQRRQQU Qwblfi M 22.52am S 303m \N XWQM QZQI J Ma Q%\ w u ww m U April 15, 1952 A s. w. ALDERSON 2,592,342

SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 15 Sheets-Sheet l4 INVENTOR Sam u eZ Wfllaersan W AM April 15, 1952 s. w. ALDERSON SHOULDER HARNESS FOR ARTIFICIAL ARMS Original Filed July 10, 1948 15 Sheets-Sheet 15 INVENTOR Samuel Wfllder son AGE T mm 6E l atentecl Apr. 15, 1952 SHOULDER HARNESS FOR ARTIFICIAL ARMS Samuel W. Alderson, New York, N. Y.

Original application July 10, 1948, Serial No. 38,018. Divided and this application May- 17, 1951, Serial No. 226,883

11 Claims. (01. 3-421) The present invention relates to electrically operated artificial arms designed for use by above-the-elbow amputees and which may be correlated with natural arm stumps resulting from amputations and varying in length from a maximum length stump to one where the amputation occurs. at or near the shoulder joint.

This application relates to subject matter found in a copending application Ser. No. 38,018 filed July 10, 1948, of which. this application is a division, U. 5. Patent No. 2,580,987. Generally speaking, above-the-elbow amputees may be classified in two groups, one group comprising amputees who possess an upper arm stump of sufficient length and with sufficient muscular function that it may lift and guide the artificial arm naturally throughout a wide variety of posi tions with little or no assistance being required by extraneous body movements on the part of the amputee. The other group consists of amputees who have an extremely short stump, no stump at all, or a stump of moderate length but with impaired muscular function. These two classes of amputees may be referred to as normal and extreme cases, respectively.

The present invention in one form thereof is designed to accommodate amputees of the first group, and in another and modified form is adapted to accommodate amputees of the second group.

It isamong the principal objects of the present invention to provide an electrically driven artificial arm including an upper arm section, a forearm section, a wrist section and a hand section, together with means whereby four distinct z Another object of the invention is to provide an electrical arm capableof the alcove mentioned movements in which any one of them may be selectively performed without disturbing orothere wise afiecting the others.

Another object of the invention is to provide.

an electrically driven arm of typewherein the motive force by means of which th? electrical arm is powered consists of a relatively small light-weight compact motor which iswholly OQLX.

- tained within the forearm section of the arm in types of motion may be imparted to the arm,

such motions consisting of (1) elbow fiexion, i. e., pivotal movement of the forearm section relative to the upper arm section; (2) hand flexion, i. e., pivotal movement of the hand section relative to the wrist section; (3) hand and wrist pronation, i. e., rotational movements of the hand and wrist section as a unit relative to the forearm section about the longitudinal axis of the latter, and (4) opening and closing movements of the fingers which constitute a part of the hand section.

An equally important object of the invention is to provide an artificial arm of the character outlined above in which the Various relative movements of which the arm is capable of performing are accomplished solely by the power derived from a single electric motor, thus relieving the amputee from the application of fatiguing muscular power and difficult or awke ward gymnastic motions.

the elbow region thereofand which in the as: sembled. arm is completely concealedfrom view. Another and important object oftheinvention is to provide a. novel type of. selective clutch mesh; anism likewise wholly contained within the fore-.- arm section for selectively controlling by a com-v mon drive from the motor thev four independent types of arm movement briefly outlined above,

A still further object of the invention is topmvide an electrical arm of this type in which the: selective clutch mechanism. consists of a sel-f-. contained unit capable of being. installed in or removed from the arm with facility as a unit and which, when installed, is mounted in the forearm section by a resilient floating connection, thereby reducing vibration and protecting the same from possible shock and, as a consequence, contributing toward the elimination of noise. A similar and related object is to provide an electrical arm in which the motor is lilrewisemounted within the forearm section by aresilient floating connection to further reduce vibration and at: tendant noise factor.

Yet another object of the invention is to pro: vide an electrical arm capable of the. four hide! pendent types of motion set forth above in which the motions may be reversed at the will of the amputee by the simple expedientof reversing the direction of rotation of the motor shaft while maintaimne any e c th Se ected ty e 0! trol in effect.

Still another object of the invention istopro: vide an electrical arm capable of the four inde: pendent motions outlined above and in which three of them, namely, the driving connections for c mp i r s fl io ha and wrist pronation, and finger movements, are self-dock: ing by a high ratio worm drive so that heel; thrust. existing by virtue of theappllcation of counter torque or pressure to any component movable part of the arm will not be carried through to the selective clutch driving. mecha-r. nism, thus eliminating cumbersome and expen: sive independent locking mechanisms which are ordinarily rovided in other types of power driven artificial arms.

A specific object of the invention is to provide an electrical arm having a hand section which closely simulates the natural hand both in shape and cosmetic appearance and in which a major group of fingers comprising the index and middle fingers are opposed to the thumb and may be moved bodily in unison relative to the thumb for the purpose of grasping objects therebetween and releasing them.

Another object of the invention is to provide an artificial arm having such a hand section in which the minor group of fingers, i. e., the ring and little fingers, are articulated in such a manner that the phalanges thereof are capable of movement relative to each other, thus permitting the fingers to assume a number of natural positions as determined by the will of the user. According to the invention, these fingers have no connection with the driving motor but are merely capable of being preset to predetermined desired positions.

Another specific object of the invention is to provide an artificial arm having a hand section in which the thumb is capable of assuming a plurality of releasable but locked positions so as to cooperate with the major group of fingers in such a manner as to accommodate the grasping of relatively large objects, such as a glass or tumbler, therebetween or of relatively small objects, such as a pencil or a sheet of paper.

Another object of the invention is to provide anartificial arm having a hand section and a wrist section, which sections are capable of continuous rotation or pronation in unison as a unit in either direction relative to the forearm, thus enabling the amputee to perform such operations, as for example, the insertion or removal of a light bulb from a lamp or wall socket, the use of a rotary tool, etc., without having to resort to oscillatory pronation and intermittent finger release as is the case with the natural hand.

Another object of the invention is to provide an. artificial arm including a selective clutch mechanism, as outlined above, in which one of the clutch elements serves to effect elbow flexion and in which a friction locking device is employed to prevent fiexion of the forearm relative to the upper arm when the driving motor is not in the actual driving process.

Another object of the invention is to provide an artificial arm having an elbow drive train of gears together with a limit stop which cooperates with the driving train to determine the maximum amount of elbow fiexion permissible.

Another object of the invention is to provide an artificial arm including a selective clutch mecha nism of the type briefiy outlined above in which selection of the particular type of motion desired may be made under the control of a series of contacts adapted to be operated by relative movement of an anatomical part of the body, as for example, the big and little toes of one foot of the amputee.

Another object of the invention is to provide an electrical control for initiating energization of the driving motor and also for causing reversal of the motor under the control of the biceps muscle of the upper arm stump of the amputee or, in an extreme case where the amputee has no stump, movement of the toes on the other foot of the amputee which is not employed for effecting selective control as outlined above. Another related object of the invention is to provide an electrical over-all control in the form of an actuator switch for rendering the selective and operational controls inoperable, such switch serving to start or stop the various movements of the electrical arm as required.

Another object of the invention is to provide a novel means for supporting an electrical arm on the upper arm stump or shoulder of an amputee in which the weight of the arm is distributed over widely separated points on the body of the user to alleviate the effort required on the part of the amputee to raise or lower the arm, as well as to prevent separation of the arm from the body.

Another object of the invention in the modified form thereof is to provide an electrical arm for extreme case amputees having means associated therewith for locking the forearm section against horizontal swinging movement when the forearm is fiexed less than a predetermined degree of fiexion relative to the upper arm but which will permit such swinging movement when the angle of fiexion exceeds the predetermined degree. By such as arrangement the amputee is afforded certain latitude of manipulation heretofore unattainable in conventional artificial arms.

Another object of the invention in the modified form thereof is to provide an artificial arm for extreme case amputees in which elevation of a shoulder blade will serve to raise the arm bodily as a whole. A related object of the invention is to provide an arm of this character is which horizontal swinging movements of the upper arm are effectively prevented when the arm is raised but are permitted when the arm is lowered to a pendant position in order that the extended artificial arm may swing in a normal mannersimulating that of a natural arm during the natural gait while walking.

In carrying out the above mentioned objects, very briefly, the electrical arm proper includes four main sections, namely, an upper arm or stump-receiving section, a forearm section, a wrist section and a hand section. The upper arm or stump-receiving section is hingedly secured to the forearm section by an elbow joint. The wrist section is rotatably attached to the forearm section in axial aligmnent therewith. And the hand section is hingedly secured to the wrist section by a wrist fiexion joint.

The hand section includes a series of fingers including a minor finger group comprising an articulated little finger and an articulated ring finger, these fingers being capable of independent movement so as to assume various convenient positions. The hand section also includes a substantially rigid mechanically movable major finger group comprising the index and middle fingeraand a substantially rigid thumb which opposes the index and middle finger group. The major finger group is capable of movement relative to the thumb to permit objects to be grasped between the fingers. The thumb is capable of being locked in either of two positions relative to the movable finger group to accommodate the grasping of objects of varying thickness. The forearm section is divided into a forearm proper and an elbow section, the latter enclosing a small electric motor and the former having disposed therein a selectively operable multiple clutch mechanism which is operatively connected to the motor and from which there extend four independent series of output gearing, one series constituting a means for affording elbow fiexion, another series constituting a means for providing continuous hand and wrist pronation, another The selective clutch mechanism referredto above is reversible in all four phases of its operation. electrical control means for selec-' tively actuating the clutch mechanism is provided under the control of the amputee. A novel form ofswi't'ch mechanism is located in one of the shoes or the user and may be manipulated by the toes for selectively operating the clutch mechanism to obtain the desired motions of the component parts of the arm. In the case of an amputee hav ing a sufficiently long above-the-elbow stump including an active biceps, the stump section has associated therewith a stump switch adapted to be operated by a partial tensing of the stump biceps to provide a master control capable of energizing or deenergizing the motor so that motion or no motion of the arm is effected, as desired. The stump switch is also used to control the direction of motion of the component parts of the arm after a selection of the type of motion desired has been made by the electrical foot controls; I

To maintain the electrical arm firmly in position on the body of the user and to prevent disarticulation between the upper arm section and. stump and also to equitably distribute the weight of the arm about the body of the user, a cooperating shoulder harness and pelvic support is provided. The shoulder harness is operatively connected to the upper arm section of the electrical arm by a sliding hinge connection and is also connected to the pelvic support by a, semi-rigid connection so that the weight of the arm is distributed between the shoulder and pelvic regions of the amputee. The specific nature of the shoulder harness and pelvic support will be varied to satisfy the exigencies of the individual amputoo, but in any case, the essential features of the invention are at all times preserved.

In the accompanying fifteen sheets of drawings forming a part of this specification, several embodiments of the invention have been illustrated'. These various embodiments differ only insofar as the electrical control for the arm is concerned and, in the main, the electrical arm proper is substantially the same.

In the drawings: Y

Fig. 1 is a perspective view of the electrical arm proper showing the same being worn by a rightarm amputee having an upper arm stump of substantial length and also showing the harness by means of which the arm is retained on the body of the user.

Fig. 2 is a view similar to Fig. 1 showing the amputee seated and illustrating the manner in which the movements of the arm may be controlled by manipulation of the feet. In this view, the arm is shown in a raised position.

Fig. 3 is a view similar to Figs. 1 and 2 show Fig. 5 is a fragmentary top plan view of the structure shown in Fig. 4 and including dotted line illustrations of internal structureof the arm mechanism, together with suitable legends therefor.

Fig. 6 is a schematic viewof the various drive mechanisms and clutches employed in connec tionwith the electrical arin' illustrating the man-- ner'in which the desired arm movements may be attained upon proper'clutch selection. I

Fig. 7 is a schematic end view of the selectiveclutch mechanism employed in connection with the present invention with the clutch centers in their proper positions.

Fig. 8 is a fragmentary enlarged detailed sectional view taken longitudinally through the el-' bow jointstructure and a portion of the forearmsection proper showing the electric'inot'o'r, the main driving shaft and a portion of the selecting devices for the selective clutch mechanism employed in connection with the electrical arm.

Fig. 9 is a sectional view taken substantially along the line 9-9 of Fig. 8.

Fig. 10 is a sectional view taken substantially along the line Ill -10 of Fig. 8. I

Fig. 11 is a sectional view taken substantially along the line H-'-ll of Fig. 10 and showing in detail a radial clutch actuating armemployed inconnection with the present invention.

Fig. 1-2 is 'a fragmentary plan view of the elbow joint structure. In this view, portions of the outer casing have been broken away to more clearly reveal the nature of the invention.

Fig. 13 is a side elevational view Of the structure shown in Fig. 12 with the casing being sim ilarly broken away.

Fig. 14 is an end view of the structure shown in Fig. 13 with the casing broken away in parts.

Fig. 15 is an end view of the motor unitemployed in connection with the present invention.

Fig. 16 is an enlarged detail sectional-view taken substantially along the line Iii-l6. of Fig. 8.

Fig. 17 is a sectional view taken substantially along the line l'|l| of Fig. 5.

Fig. 18 is a side elevational view of the structure shown in Fig. 17 with the casing broken away. This view shows the hand and wrist pronation drive mechanism.

Fig. 19 isa detailed sectional view of one of the clutch units proper employed in connection with the present invention.

Fig. 20 is a fragmentary view of a portion of the electrical arm in the vicinity of the wrist section thereof showing the mechanism for attaining hand fiex'ion and for manipulating the fingers.

Fig. 21 is a sectional view taken substantially along the line 2|-2l of Fig. 20 illustrating the hand fiexion and hand and wrist pronation driv ing mechanism.

Fig. 22 is a plan view of an inner sole employed in connection with the present invention and adapted to be worn by the amputee in his shoe for controlling a series of electrical toe contacts by means of which various movements of the arm may be attained.

Fig. 23 is a sectional view taken substantially along the line 2323 of Fig. 22.

Fig. 24 is a sectional view taken substantially along the line 24- 24 of Fig. 20-. n

Figs. 25, 26, 27 and 28 are fragmentary sectional views somewhat schematic in their representation illustrating the operation of a'sel'flocking thumb constructionemployed in connec- 7 tion with the present invention and which is capable of being prepositioned to satisfy the preference of the user.

Fig. 29 is a sectional view taken substantially along the line 29-49 of Fig. 6.

I Fig. 30 (adjacent Fig. 1) is an enlarged fragmentary view of a portion of the upper arm section of the electrical arm illustrating the manner inwhich a stump switch employed in connection with the invention may be manipulated by the biceps muscle of the amputee.

Fig. 31 is a circuit diagram of the electrical connections for the arm.

Fig. 32 is a fragmentary front elevational view of a modified form of supporting mechanism for the electrical arm and designed for use by stumpless amputees or for amputees having extremely short upper arm stumps.

Fig. 33 is a sectional view taken substantially along the line '3333 of Fig. 32.

Fig. 34 is a side elevational view of a locking device employed in connection with the modified form of the invention.

Fig. 35 (adjacent Fig. 22) is a fragmentary view similar to Fig. 22 showing a portion of an inner sole adapted to be worn by an extreme case or stumpless amputee in his shoe for effecting certain electrical controls associated with the electrical arm.

Fig. 36 is a circuit diagram or" the electrical connections for the electrical arm when employed by an extreme case amputee.

In all of the above described views like characters of reference are employed to designate like parts throughout.

BRIEF DESCRIPTION Referring now to the drawings in detail and in particular to Figs. 4 and 5, the electrical arm involves in its general organization a rigid upper arm structure fragmentarily shown at Ill, a rigid forearm structure or assembly i2, a wrist assembly it and a hand assembly Hi. The forearm assembly l2 includes a forearm section proper l8 and an elbow joint structure or assembly 2;], the latter being pivotally connected as at 22 to the upper arm structure ill. The wrist assembly It is coaxial with the forearm section 13 and is pivotally connected to the free end of the latter for rotational movements in either direction about the common axis of the two sections by means of a pronation joint structure 24? which is common to the two sections.

The wrist assembly l4 and hand assembly 15 are pivotally connected together by a hand fiexicn joint 26. The hand assembly it includes a palm portion 26 and four independently movable digit or finger sections including a rigid thumb 3i] pivotally secured as at 32 to the palm portion 2s, a multiple articulated little finger 34, a multiple articulated ring finger 36 and separately molded index and middle fingers 38 and 59 respectively, which are movable in unison relative to the palm portion 28. As shownin Fig. 5, the index, middle, ring and little fingers are pivoted for swinging movement relative to the palm portion 28on a common finger pivot in the form of a pintle pin Still referring to Figs. 4 and 5, and also to Figs. 12 and 13, the upper arm structure Hi includes a pair of spaced parallel structural members 46 and 46 which are pivotally attached by means of the connection 22 to the elbow joint-structure 20 and which serve to support therebetween a tubular stump-receiving socket or casing 48 (see also Figs. 1, 2, 3 and 30). The elbow joint structure 28 is in the form of a casting 2| having a removable cover 23 and which contains the electric mo tor M (Fig. 8) by means of which all the operative movable instrumentalities comprising the electrical arm are selectively driven at the will of the amputee. This structure 20 also contains certain gear reduction mechanism and the gearing by means of which elbow flexion takes place and which will be described in detail subsequently.

The forearm section proper I8 involves in its general organization a forearm framework designated in its entirety at 59 (Figs. 17 and 18) which serves to support thereon a pair of forearm covers 52 and 51.1 which may be of a sound-proof nature and which serve to enclose various clutch and gearing mechanisms, as well as certain electrical instrumentalities, the nature of which will be fully described hereinafter.

The pronation joint structure 24 in the main is in the form of a bearing member having counterparts associated with both the forearm section proper It and the wrist assembly M. The wrist assembly is is in the form of a tubular cosmetic shell or casing 56 and within this casing there are disposed certain hand fiexion driving mechanism,

as well as the pivotal connection 26 for the palm portion 28. A train of driving mechanism leading from the motor M to the major finger group 38, it also passes through the wrist shell 56.

The palm portion 28 is in the form of a twopiece separable cosmetic shell 58, 59 in which is disposed the immediate finger driving instrumentalities, including the pivotal connections 32, 42 for the various fingers of the hand. The thumb 353 is in the form of a hollow molded cosmetic shell, as are both the index and middle fingers which operate in unison. The little and ring fingers 3t, 35 are of an articulated type and are designed for independent positional movements and the nature of these fingers will be set forth subsequently.

A shoulder harness is designated in its entirety at 60 (Fig. 3) and has flexible connections with the upper arm structure 10 which prevents separation between the stump and stump-receiving socket 48 and a semi-rigid connection with a pelvic suspension device 66. The shoulder harness EB and pelvic suspension device 66. together with the connections between them, serve to distribute the entire weight of the electrical arm between the shoulder and pelvic regions of the amputee.

The electrical arm is powered by means of a small, compact, portable battery unit B (Figs. 2 and 31) adapted to be conveniently carried .in the trousers pocket 68, preferably on the same side as the amputation. The control of the various movements of the electrical arm is effected by means of a series of electrical contacts contained in one of the shoes of the user, as for example, the right shoe l6, and also under the control of a stump switch assembly 72 (Figs. 1, 2, 30 and 31). The control contacts in the shoe are utilized for the purpose of effecting the selected type of movement for the various parts of the arm, while the stump switch is employed to initiate the selected type of movement as well as for selecting a forward or reverse movement, all in a manner that will be made clear presently.

THE MOTOR, MOTOR DRIVE AND SUP- PORTING STRUCTURE THEREFOR Referring now to Figs. 8, 12, 13, 14 and 15, the motor M, which is of the direct current, reversible, permanent magnet type, is supported within the elbow joint structure 28 by means of a resilient floating connection. The elbow joint structure 28 includes a base casting 2| which is of box-like configuration and which has an open upper end adapted to be closed by means of a cover plate 23. The forward end of the elbow joint structure is provided with a rectangular channel portion I8 affording an external groove 88 adapted to receive therein a suitable sealing gasket 82 (Figs. 8 and 13) which may be formed of soft rubber or the like, and which affords a seal for the forearm section proper I8 when the cover plates 52 and 54 are in position.

The motor M is in the form of a substantially rectangular box-like casing which is bolted or otherwise secured as at B6 to a gear reduction assembly 88, likewise of box-like configuration, and which is mounted by means of a floating connection from the casting 2|. The floating connection just referred to includes an upstanding bracket 88 which is secured to the end wall 92 of the casting 2| by means of through-bolts 84 and which is spaced therefrom by means of spacing collars 86. A plurality of attachment plates 98 are secured to the bracket 88 by means of studs I88 and these attachment plates 98 are fastened to respective supporting pads I82 which may be formed of resilient material such as rubher. The supporting pads I82 are fastened to respective attachment bosses I84 carried on the casing of the gear reduction assembly 88 and thus the gear reduction device and the motor are yieldingly supported from the casting 2| with the solid resilient pads I82 constituting the sole supporting means for the motor and gear reduction assembly.

The gear reduction device 68 is provided with an output shaft I88 which is connected through a resilient coupling I88 to a floating shaft II8 which in turn is connected through a second resilient coupling II2 to a shaft I I4, which may be regarded as the main drive shaft leading to the various gear train mechanisms employed for effecting the desired movements of the component parts of the electrical arm.

THE SELECTIVE CLUTCH ASSEMBLY Referring now to Figs. 6, 7, 8, 9, 12, 13, 17, 18 and 19, the selective clutch mechanism is designated in its entirety at I28 in Figs. 17 and 18, and is a unitary self-contained assembly which is mounted within the forearm section proper I8 by means of a floating connection. The drive shaft [I4 constitutes the input drive for this clutch assembly.

v The clutch assembly involves in its general organization a rigid but floating frame-like structure I22 including a front end plate I24 (Figs. 6 and 18), a medial plate I26 and a rear end plate I28 (Figs. and 12). The plates I24 and I26 are connected together by means of spacing members I38 and the medial plate I26 and end plate I28 are connected together by means of spacing members I 32. The end plate I 24 is provided with a pair of laterally extending ears I34 which are supported from a pair of longitudinally extending parallel frame members I36 and I38 integrally formed with an end piece in the form of a ring I38 constituting a part of the forearm framework 58. The frame members I36 and I38 are generall of channel-shaped construction to lend strength to the structure and they may be integrally cast with one element of the pronation joint structure 24 at the front of the forearm section proper I8. At the rear of the forearm section the members I36 and I38 are .secured to a pair of block members I48 and I42 respectively, and these block members in turn are secured to the inner surface of the elbow joint structure 28 on opposite sides thereof and thus the members I36 and I38 serve to maintain the pronation joint structure 24 spaced from the forward end of the elbow joint structure 28.

The clutch mechanism proper I28 includes a series of four clutch elements I44, I46, I48 and I 58. The clutch element I44 is adapted to .go into operation to effect the elbow drive or. in other words, to attain elbow flexion. The clutch I46 is adapted to go into operation to effect hand and wrist pronation at the pronation joint. 24. The clutch I 48 is adapted to go into operation to effect opening and closing movements of the index and ring finger assembly relative to the thumb. The clutch I 58 is adapted to go into operation to effect hand flexion, all in a manner that will presently beset forth.

The clutch elements I 44, I46, I48 and I58 are substantially identical in construction and are mounted in the floating clutch assembly I22 at substantially equally spaced points arranged about a common center and these elements occupy the same transverse plane.

Each clutch element includes a supporting shaft I52 which is rotatably journaled in the front and medial plates I24 and I26. The clutch elements are of the reverse acting type, that is to say, the driven element of the clutch may coact with the driving element thereof to effect rotation of the clutch elements in opposite directions to reverse whichever character of motion of the electrical arm .is selected. A driven element I54 is mounted upon and secured to the shaft I52. This element is in the form of a circular disc having outwardly projecting clutch teeth I56 on one side thereof. These teeth op pose a series of similar teeth provided on the driving element I58 of the clutch. The driving element is similar in configuration to the driven element and is rotatably mounted on the shaft I52 in close proximity to the driven element. Each driving element includes an integrally formed gear I68 and all four of the gears I68 are in constant.mesh with an idler gear I62 mounted on a shaft I63 rotatably journaled in the front and medial plates I24, I26. The gear I68, which is integrally formed with the clutch I48 and which controls the opening and closing movements of the fingers, meshes with a driving gear I65 mounted on the drive shaft II 4 and thus when the motor is energized and the drive shaft 4 is rotated, a drive is transmitted from .the gear I65 to the gear I68 of the clutch I48 and from thence through the idler gear|62to all of the clutch elements I58 so that these elements rotate in unison.

When the arm is at rest and no relative motion between any of the component parts thereof is contemplated, .the drive shaft I I4 remains stationary due to lack of energization of the motor M. .As soon as a selected movement of the arm is contemplated, the motor M is energized by means of a suitable control to be described subsequently and the drive shaft I I4 commences to rotate in the selected direction, thus causing all four of the driving gears I68, and consequently all four of the driving elements I58, to rotate in unison. Until one of the clutches I44, I46, I48 or I58, as the case may be, is thrown into meshing engagement no movement of any parts of the 

